This invention relates to an apparatus for improving the operational performance of a machine, device or the like, and, more particularly, to an such apparatus for compensating for positioning, pointing and/or orientation errors caused by defections of structural members and components of a high performance machine or device and/or for reducing vibration inputs to such machine or device and/or for micro-positioning such machine or device so as to improve the operational performance thereof.
Typically, high performance machines, devices, components or the like, may have to perform or maneuver at relatively high speeds and/or accelerations and/or may be subjected to input disturbances. To attain such high speeds and/or accelerations, it is desirable to make these machines light weight. A by product of the weight reduction is the added structural flexibility even though relatively light weight and relatively stiff materials, such as, advanced composites and ceramics are utilized. Such machines or devices may include ultra-high speed and accuracy machine tools, positioning tables, precise pointing devices such as gun barrels, spacecrafts and rotorcrafts, robotic manipulators, cranes, quality control and measurement systems, machinery used in the electronics industry such as probes, lead bonding, laser and x-ray litiography, and so forth, and similar high performance products and computer controlled machines.
When operating at relatively high speeds and/or accelerations, the above-described machines may have structures and/or components that behave as relatively flexible. Such relatively flexible structures may adverse affect the operational performance, that is, the attainable level of operating speed and/or acceleration, and/or positioning accuracy and/or orientation accuracy and/or pointing accuracy of such machines or devices. Further, as a result of such flexibilities, such machines or devices may have vibration, stabilization and control problems which could adversely affect the performance of the machines. Further, insufficient vibration damping may also adversely affect the positioning, pointing or orientation accuracy of such machines or devices by requiring a relatively long settling time for such vibration to xe2x80x9csettle outxe2x80x9d. Therefore, desired or required positioning, pointing or orientation (or tracking) accuracies or settling times may not be achievable, thus resulting in relatively poor operational performance.
As an example, consider the situation in which it is desired to point a gun barrel of a turret weapon system. During aggressive maneuvering and firing, the gun barrel behaves as a relatively flexible beam. Such flexibility can result in structural vibration which ultimately affects the pointing accuracy of the tip of the gun barrel. Although the turret weapon system may have a main actuator(s) for providing movements, such main actuator is not located at the tip of the gun barrel. As a result, the main actuator drives the tip of the gun barrel through the relatively flexible gun barrel, that is, the actuator is non-collocated with the tip of the gun barrel. As a result of such non-collocation and/or non-linearities (such as, stiction, friction, backlash, non-linear elasticity due to drive train, and so forth) between the tip of the gun barrel and the main actuator, it is relatively difficult, if not impossible, to achieve high pointing accuracy. Furthermore, the main actuator may also not have the required bandwidth to correct for the structural modes of vibration particularly those affecting pointing accuracy.
As another example, consider positioning and/or orientation of an end-effector of a robotic manipulator. In this situation, at relatively high operating speeds and/or accelerations, the links between the joint actuator(s) and the end-effector behaves as a flexible member. As such, in this situation, the joint actuator(s) is non-collocated with the end-effector. Similarly, in this situation, the excitation of a structural mode or modes due to the vibration thereof may seriously affect the positioning or orientation accuracy so as to adversely affect the operational performance of the robotic manipulator.
Therefore, as is to be appreciated, it is desirable to compensate for adverse effects of deflections in structural members and components due to the above-described vibration and structural flexibility of such machines, devices or components so as to improve the operational performance thereof. In an attempt to improve such operational performance, various control techniques or systems have been suggested or utilized. However, such control systems normally result in only a limited amount of improvement in the operational performance of the respective machine or device.
Further, high performance machines, devices or the like may be subjected to externally generated vibration (which may be high frequency vibration) which may adversely affect the operational performance of such machines or devices. In an attempt to reduce such vibration, vibration isolation systems have been developed which may reduce the vibration inputs to a machine or device along one direction. However, such vibration isolation systems may not adequately reduce or attenuate vibration inputs if such vibration inputs are along two or more directions. Additionally, such vibration isolation systems may have limited bandwidth.
Thus, the prior art has failed to provide an apparatus for compensating for positioning, pointing and orientation errors caused by deflections of structural members and components of high performance machines or devices and for reducing vibration inputs to a device. As such, the prior art has failed to provide an apparatus for improving the operational performance of high performance machines, devices and components.
An object of the present invention is to provide an apparatus for improving the operational performance of a machine, device or the like which overcomes the problems associated with the prior art.
More specifically, it is an object of the present invention to provide a compensating apparatus coupled to a deflectable member of a machine, device or the like having at least one active-type actuator which is adapted to exert a relatively high corrective moment and/or force and/or torque on the deflectable member so as to compensate for the deflection thereof.
Yet another object of the present invention is to provide a compensating apparatus as aforesaid which is adapted to provide a relatively fast response time.
A still further object of the present invention is to provide a compensating apparatus as aforesaid in which the active-type actuator(s) are at least partially thermally isolated from the deflectable member.
A further object of the present invention is to provide a compensating apparatus having one or more active-type actuators attached to a flexible member at one or more positions to act as a quasi-distributed actuator.
Yet another object of the present invention is to provide a compensating apparatus as aforesaid which may operate in either an open-loop or closed-loop manner.
A still further object of the present invention is to provide an apparatus for reducing vibration inputs to a device in at least two directions.
Yet still another object of the present invention is to provide an apparatus for reducing vibration inputs as aforesaid having at least one module each including a plurality of active-type actuators and adapted to reduce vibration inputs to the device in at least two directions.
Another object of the present invention is to provide an apparatus for reducing vibration inputs as aforesaid in which two or more modules may be easily combined so as to reduce vibration inputs to the device in more than two selected directions.
A yet another object of the present invention is to provide an apparatus for positioning a device having a plurality of modules each including a plurality of active-type actuators.
In accordance with one aspect of the present invention, an apparatus for compensating for deflection of a deflectable member is provided which comprises first and second support members each coupled to the deflectable member, and a plurality of actuator devices each coupled to the first and second support members and arranged at a respective predetermined distance from the deflectable member for exerting a moment on the deflectable member so as to compensate for the deflection of the deflectable member.
In accordance with another aspect of the present invention, an apparatus for compensating for deflection of a deflectable member is provided which comprises a detecting device for detecting at least one of deflection of the deflectable member and a derivative thereof and for producing a detection signal therefrom, a control device for generating a control signal in response to the detection signal, first and second support members each coupled to the deflectable member, and a plurality of actuator devices each coupled to the first and second support members and arranged at a respective predetermined distance from the deflectable member for exerting a moment on the deflectable member in response to the control signal so as to compensate for the deflection of the deflectable member.
In accordance with still another aspect of the present invention, an apparatus for reducing vibration inputs to a device is provided which comprises a detecting device for detecting vibration along at least two directions of the device and for supplying therefrom a vibration signal corresponding to the detected vibration, a control device for generating a control signal in response to the vibration signal, a support member for supporting the device, and a plurality of actuator devices each coupled to the support member for moving the device in response to the control signal so as to reduce the vibration inputs to the device in at least two directions.
In accordance with a still further aspect of the present invention, an apparatus for positioning a device is provided which comprises a plurality of modules each having a support member and a plurality of actuator devices coupled thereto for moving the device in at least one of a translational and rotational direction, the modules being arranged in series with one another so as to move the device in more than one direction so as to position the device.
Other objects, features and advantages according to the present invention will become apparent from the following detailed description of the illustrated embodiments when read in conjunction with the accompanying drawings in which corresponding components are identified by the same reference numerals.